1. Field of the Invention
The present invention relates to a thermal analysis apparatus such as a TSC (Thermally Stimulated Current) apparatus, and temperature correction method used for the thermal analysis apparatus.
2. Description of the Related Art
The TSC apparatus mentioned above measures an electric current generated in a sample while changing the temperature of the sample. The TSC apparatus hence has a pair of electrodes which contact the sample, a device which controls the temperature of the sample, and an electric current measurement device which is connected to the pair of electrodes. This TSC apparatus is, for example, disclosed in Japanese Patent Laid-Open Publication No. 2002-156344. This TSC apparatus measures an electric current flowing through a sample in the order of femto ampere (fA=10−15A), so that information can be attained concerning the fine structure of the sample, crystal defects, and internal electronic state of the sample. For example, quantitative evaluation can be made with respect to GaAs crystal which is a high-frequency element.
In addition to the TSC apparatus described above, a DSC (Differential Scanning Calorimetry) apparatus and a DTA (Differential Thermal Analysis) apparatus are known as thermal analysis apparatuses.
The DTA is to measure a temperature difference between a sample to be measured and a reference substance while changing the temperatures of both the sample and substance. Found from this measurement are, for example, thermal changes which occur in the sample, e.g., physical changes such as fusion, transition, and the like. The DSC is to measure a calorific difference between a sample to be measured and a reference substance while changing the temperatures of both. The DSC is classified into two known types depending on the difference between their measurement methods, i.e., thermal compensation type DSC and thermal flux type DSC. Physical changes which occur in a sample can also be found by the DSC like case of the DTA.
Both of the DSC and the DTA measure physical characteristics of samples. Temperatures which belong to those physical characteristics such as melting points and the like are known from literature values. Therefore, with respect to the temperature measurement system in an apparatus which practices the DSC or the like, temperature correction can be easily carried by comparing actually measured temperatures with literature values.
In contrast, in the method of measurement, such as the TSC, in which an electric current generated in a sample is directly measured from the sample, physical characteristics of the sample are not measured, and therefore, measured temperatures based on the temperature measurement system which is constituted by using a temperature sensor, thermocouple, etc., cannot be compared with literature values. Consequently, the temperature of the sample measured by the temperature measurement system in the TSC cannot be determined to be correct or not.